1. Field of the Invention
An aspect of the present invention relates to a centrifuge which includes a single motor as a drive source and a lock mechanism for locking a cover in the two portions thereof.
2. Description of the Related Art
A centrifuge is a machine in which a rotor with a sample stored therein is driven and rotated in a rotor rotation chamber to thereby centrifuge the sample. In the centrifuge, the opening of the rotor ration chamber can be opened and closed with a cover; during the centrifuging operation of the centrifuge while the rotor is rotating, the opening of the rotor rotation chamber is closed by the cover; and, before and after the centrifuging operation, in order to charge and discharge the sample, the cover is opened.
Generally, in a centrifuge which is used in a laboratory or the like, in order to prevent the rotating rotor from being exposed, the cover, which has closed the opening of the rotor rotation chamber, is locked automatically. As a method for locking the cover, there are known two types of methods: that is, in one type, the cover is simply caught by a latch; and, in the other type, the closed state of the cover is detected and, based on this detection, a lock mechanism is operated automatically, whereby the cover cannot be opened manually.
As a drive method for driving the lock mechanism, there are known two types of drive methods: that is, in one type, the cover is latched by reciprocating it using an electromagnetic solenoid; and, in the other type, the cover is pulled in using a motor (for example, see JP-2001-300350-A).
Recently, there has been increasing the need for consideration for safety in order that, even when the rotor is broken during rotation, the broken pieces thereof can be prevented from flying externally of the centrifuge. In this respect, a lock mechanism of a motor drive type, which can provide a relatively large sealing power, is advantageous. A lock mechanism plays an important role as a portion concerned with the safety of the centrifuge, and the reliability of the lock mechanism provides an important element.
Conventionally, several kinds of lock mechanisms using a motor are put into practical use and, in many cases, depending on the intensity of the energy of the rotor and the complexity of the breaking mode of the rotor, the cover is locked in a plurality of positions thereof. In a structure where independent motors are disposed in the individual lock mechanisms according to the relationship between the lock positions of the cover, the cost of the structure is large.
In view of this, there is also proposed a lock mechanism which includes a drive side hook to be driven and rotated by a single motor and a driven side hook connected by a connecting member to the drive side hook to be rotated integrally with the drive side hook, wherein the drive side hook and driven side hook are engaged with the securing members of the cover to thereby lock the cover at two positions thereof.
In the above lock mechanism, when there is employed a structure where both of the drive side hook and driven side hook are engaged with the securing member of the cover and securing member is pulled in to thereby bring the cover into close contact with the opening of the rotor rotation chamber, the two hooks must have a large force to pull in the securing member. In this case, a drive force from the motor is transmitted from the drive side hook through the connecting member to the driven side hook, so that a large torsion torque is applied to the connecting member. Owing to this, high strength and rigidity are required of the connecting member, resulting in the increased dimension (thickness) and weight of the connecting member.